Question

What is the relation between one kilowatt-hour and joule?

Answer 1

Step 1: Definition

A joule is a unit of energy equivalent to a “$\mathrm{watt}-\mathrm{second}$”. A Kilowatt-hour is therefore $1000\times 3600\mathrm{joules}$.

($\mathrm{Kilo}=1000,$and $3600\mathrm{seconds}\mathrm{per}\mathrm{hour}$).

Step 2: Finding the relation between one kilowatt-hour and joule

According to the above definition,

$$\begin{gathered} 1\mathrm{kWh}=1\mathrm{kW}\times 1\mathrm{h} \\ =1000\mathrm{W}\times 3600\mathrm{s} \\ =1000{\mathrm{js}}^{-1}\times 3600\mathrm{s} \\ =3.6\times {10}^6\mathrm{J} \end{gathered}$$

Therefore, the relation between one kilowatt-hour and joule $1\mathrm{kWh}=3.6\times {10}^6\mathrm{J}$.